President Donald Trump mocked former President Barack Obama as being weak on Russia and standing by while Moscow illegally annexed Crimea from Ukraine in 2014.

But Russia effectively locked Ukraine out of the Sea of Azov over the weekend, and despite Ukraine's calls for NATO help, Trump has appeared to do nothing.

Trump said Russia took Crimea from Ukraine because it didn't respect Obama, but despite Trump's claiming a friendship with Russian President Vladimir Putin, Putin has done much the same to him.

Trump canceled a meeting with Putin over the incident, but it's unclear how that will help Ukraine in any way.

President Donald Trump mocked former President Barack Obama as being weak on Russia and standing by while Moscow illegally annexed Crimea from Ukraine in 2014.

But Russia's navy recently locked Ukraine out of the Sea of Azov, which Kiev relies on to feed its valuable port cities in the country's east.

Trump's response so far looks every bit as weak.

Trump said in June that Russian President Vladimir Putin "didn't respect" Obama.

"President Obama lost Crimea because President Putin didn't respect President Obama, didn't respect our country, and didn't respect Ukraine," he said.

In 2014, Russian troops without official uniforms stormed into Crimea and eastern Ukraine, cut power, interfered with electronics and communications, spread fake news, and eventually established control of the strategic peninsula.

The US under Obama responded with sanctions, condemnation, and attempts to usher in diplomacy.

But none of that worked. Ukraine, which has dreamed of joining the West as a functioning democracy and even a prospective member of NATO, remains at war with Russian soldiers whose existence Putin still denies.

Ukraine has now been at war for four years against the Russian separatist movement, which has cost it 10,000 lives and left 1.6 million people in the country displaced.

Obama refused to provide lethal aid to Ukraine, a decision that Trump reversed and often touts as a demonstration of his harder line against Russia.

But on Sunday, Russia escalated the war by using its own marked navy ships to fire on Ukraine's navy and shut down the entire Sea of Azov to any ship bound for or coming from Ukraine.

In doing this, Russia disregarded a 2003 bilateral treaty giving Ukraine and Russia exclusive rights to sail their ships in and out at will.

The fighting also saw six Ukrainian sailors wounded, and some were detained and made to give bizarre-looking confessions on Russian television.

The Russian large landing ship Azov fires missiles during a rehearsal for the Navy Day parade in the Black Sea port of Sevastopol, Crimea, on July 27, 2017. REUTERS/Pavel Rebrov

Read more: Russia is moving advanced missiles into Crimea as Ukraine warns it's under threat of a 'full-scale war'

John Herbst, a former US ambassador to Ukraine, said on a call with reporters organized by the Atlantic Council that Russia sought to take control of the Sea of Azov to choke and destabilize Ukraine's east.

Ukraine's president has since called for NATO warships to enter the Sea of Azov. He's said Putin intends to take over all of Ukraine as a colony.

Now Ukraine fears a full-scale war and invasion from Russia.

During his presidential campaign in July 2016, Trump said of Putin: "He's not going to go into Ukraine, all right? You can mark it down, and you can put it down. You can take it anywhere you want."

How Trump's handling the Azov crisis

Essentially, Moscow used a military escalation to steal another chunk of Ukraine's sovereignty, building on its past annexation of Crimea, as it now controls both sides of the pivotal Kerch Strait.

In response, Nikki Haley, the US ambassador to the UN, condemned the move and called for action.

Trump on Thursday canceled a planned meeting with Putin on the sidelines of the G20 summit in Buenos Aires, Argentina, saying he wouldn't meet Putin until the sailors were returned and the situation resolved.

But no real action has come forth yet to stop Russia's destabilization of Ukraine.

NATO hasn't responded to Ukraine's calls to send ships. Meanwhile, Russia has blocked Ukraine's two most important ports on the Azov.

As the Azov is an inland sea, not international waters, and requires both Russian and Ukrainian approval for foreign vessels to legally enter, NATO doesn't have a straightforward case for entering the sea.

A slew of treaties also keep the US from flooding Ukraine with weapons to fight back against Russia, but Russia has shown little regard for its own treaties in making the land and sea grabs.

Indeed, the US and NATO would be in a better place to respond to the Sea of Azov crisis if they had met Russia's 2014 Crimea annexation with more resolve, but that still doesn't bode well for Trump's hypothesis that Putin respects him and not Obama.

"Crimea was TAKEN by Russia during the Obama Administration. Was Obama too soft on Russia?" Trump tweeted in February 2017.

But despite the respect and friendship Trump claims to have with Putin, Moscow has effectively taken the Sea of Azov from Kiev's hands, and Trump looks nowhere close to action.