Martial Law in Ukraine as Trump Threatens to Cancel Putin Meeting

Ukraine's president signed an act imposing martial law in border regions on Wednesday as mounting tensions over Russia's seizure of Ukrainian ships saw US President Donald Trump threaten to cancel talks with Vladimir Putin, reports AFP.

President Petro Poroshenko's spokesman confirmed he had signed the act, which introduces martial law for 30 days in 10 regions bordering Russia, the Black Sea, and the Azov Sea.

The move came after Poroshenko warned of a build-up of Russian forces near Ukraine's borders, escalating the most dangerous crisis in years between the ex-Soviet neighbours.

Western governments have accused Russia of acting illegally in seizing the three ships and Trump has said he is considering canceling planned talks with Putin at this week's G20 summit in Buenos Aires.

Trump said he would make a final decision after hearing a report from national security advisors on this weekend's incident.

"That will be very determinative," Trump told the Washington Post. "Maybe I won't have the meeting."