According to Western estimates, 5 possible scenarios for the Russian war on Ukraine

Russia's war on Ukraine began more than 3 weeks ago, and Russian forces are still receiving stiff resistance from Ukrainian forces around the capital, Kyiv, and other major cities such as Kharkiv (east) and Mariupol (south).

The following are the possible scenarios for what might happen later, according to the estimates of Western governmental and military sources, and experts from research centers.

1- Military Trouble

The Ukrainian forces are still resisting the Russian forces and incurred heavy losses in equipment and many.

The Ukrainians decisively repulsed an attempt by paratroopers to capture the capital in the early days of the war before retreating since then to defensive positions that enabled them to maintain control of all strategic cities.

Although Russia has long claimed air supremacy, it appears that Ukraine's air defenses are still operating, while Western countries continue to supply them with portable anti-tank and anti-aircraft missiles.

"The Russian invasion has largely bogged down on all fronts," a British Ministry of Defense report said on Thursday.

US intelligence estimates that 7,000 Russian military personnel have died, the New York Times reports, although experts say these numbers should be treated with caution.

On Wednesday, US President Joe Biden announced a huge new package of military aid to Ukraine, including S-300 air defense missile systems, 100 "Suicide" Switchblade drones, and thousands of other missiles.

But the Ukrainian military resistance has a high civilian cost. Thousands were killed and cities such as Mariupol and Kherson (south) were destroyed.

2- peace agreement

Negotiators from both sides began talking just days after the war began, first at the Belarus-Ukraine border, then in Turkey, and finally in the capital, Kyiv (via video technology).

Mounting battlefield losses and Western sanctions stifling the Russian economy may prompt President Vladimir Putin to search for a face-saving way to end the conflict.

Rob Johnson, a war expert at Oxford University, wrote this week that “Ukraine may be able to force Russia to make a choice: go on and incur irreparable losses, or stop and strike a peace deal that achieves some of its goals.”

For his part, Russian Foreign Minister Sergei Lavrov said - on Wednesday - that the two sides are "on the verge of agreeing" on a deal in which Ukraine will accept to be a neutral country, along the lines of Sweden and Austria.

Ukrainian President Volodymyr Zelensky has publicly acknowledged that his country will not join NATO, a key demand of the Kremlin.

But although the chances of reaching an agreement have greatly increased in recent days, there is no indication that a ceasefire will be reached;

Ukraine wants a full Russian withdrawal and security guarantees for the future.

Some critics of Putin see him as using diplomacy as a cover to continue the war.

3- Change in the Russian interior

Putin is tightening his grip on Russian society.

The campaign against independent and foreign media has reinforced the dominance of Russia's ultra-power-loyal state media.

Thousands of anti-war protesters were arrested, and a new law was passed providing a prison sentence of up to 15 years for anyone who spreads "fake news" about the military.

But there are signs of cracks in the ruling elite, with some oligarchs, parliamentarians and even the private oil group Lukoil publicly calling for a ceasefire or an end to the fighting.

A Russian journalist carried a banner reading "No to war" during the prime-time news broadcast on state television this week.

The possibility of Putin's fall in a violent popular protest or even a coup from within cannot be ruled out, but that does not seem likely at this point.

"His (Putin's) personal security is very good and will remain good until the moment things change," said Eliot Cohen, a researcher at the Center for Strategic and International Studies in Washington.

"This has happened many times in Soviet and Russian history," he added.

4- Russian military success

Given the superior armaments of the Russian forces, air power and indiscriminate use of artillery, Western defense analysts believe it can continue to advance.

Last Wednesday, a senior European military official warned against underestimating the ability of Russian forces to renew and adapt their tactics.

The official said that it appears to have logistical and moral problems with a shortage of fuel and even motor oils.

"But we must not ignore that all this does not change the superiority of the Russian army," he added.

Moscow is openly recruiting mercenaries from Syria to support its forces, and also uses the highly-ambiguous private "Wagner" military group.

But even if the Russians took control of strategic cities like Kyiv or coastal Odessa (southern), Putin would then face the challenge of continuing to occupy them.

5- Expansion of the conflict

Ukraine borders with 4 ex-Soviet states that are now members of the US-led NATO, of which an attack on one member is an attack on all.

Putin's nostalgia for the Soviet Union and his pledge to protect Russian-speaking minorities - also found in the Baltic states - raises an open question about his regional ambitions.

Few would expect Putin to directly attack a NATO member, which would risk a nuclear attack, but analysts have warned of Russian provocations that fall short of igniting a war.

Putin ordered Russia's nuclear deterrent to be put on high alert, and Foreign Minister Lavrov warned that "the Third World War can only be a nuclear war."

Western analysts say such warnings should be seen as a deterrent to the United States and Europe from considering proposals such as imposing a "no-fly zone" over Ukraine.