A gaffe-prone former Japanese prime minister arrived in Crimea Tuesday despite stiff opposition from Tokyo to a trip that could be seen to legitimize Moscow's annexation of the Black Sea peninsula.

Japanese Foreign Minister Fumio Kishida told reporters earlier Tuesday that the government was trying to stop ex-premier Yukio Hatoyama from making the trip amid fears he might muddy diplomatic waters.

Polish and Latvian officials on Tuesday voiced skepticism over calls for a European Union army to counter a militarily resurgent Russia.

"It's a very risky idea," Polish Foreign Minister Grzegorz Schetyna told Poland's private Radio Zet in reaction to Sunday's proposal by European Commission head Jean-Claude Juncker.

The top U.S. diplomat for Europe declared Tuesday that Crimea and parts of eastern Ukraine were subject to a "reign of terror", blaming Russia for a conflict that has claimed thousands of lives.

"Even as Ukraine is building a peaceful, democratic, independent nation across 93 percent of its territory, Crimea and parts of eastern Ukraine are suffering a reign of terror," Assistant Secretary of State Victoria Nuland told the Senate Foreign Relations Committee.

Both sides in the conflict in eastern Ukraine have withdrawn most of their heavy weapons from the frontline, bolstering a month-old truce, Ukrainian President Petro Poroshenko has said.

In an interview with state television Monday evening Poroshenko said government forces had "withdrawn the lion's share of multiple launch rocket systems and heavy artillery."

Poland on Tuesday criticized a Swiss company's sale of high-tech camouflage netting to Russia despite Western sanctions over its role in the Ukraine conflict.

"It must be condemned... supplying this kind of equipment facilitates the aggression of the Russian military," Foreign Minister Grzegorz Schetyna told PAP news agency of the 85 million euros ($91 million sale).

Russia could pose the "single greatest threat" to Britain, Foreign Secretary Philip Hammond warned in a speech Tuesday, while criticizing "apologists" for Islamic State (IS) group militant "Jihadi John".

Hammond accused Russian President Vladmir Putin of "subverting" international rules which keep the peace between nations and said his actions in Crimea and eastern Ukraine "fundamentally undermine" the security of eastern European states.

President Vladimir Putin said Monday that Russia took over Crimea because it had to protect Crimea's mostly ethnic-Russian population after pro-Western Ukrainian nationalists came to power in Ukraine.

In the latest preview extracts of an upcoming documentary called "Homeward bound" on state-run Rossiya-1 television, Putin portrayed Russia's military takeover and annexation of the Ukrainian province as a rescue mission.

Russia has vastly enhanced its military capabilities in Crimea since annexing the peninsula, turning it into a "power projection platform," a senior NATO general was reported Monday as saying.

"What we've seen is easy to describe as the militarization of Crimea," the alliance's top commander for Europe, General Philip Breedlove, said in an interview with Ukrainian channel 1+1.

Russian President Vladimir Putin on Monday awarded a medal of honor to the chief suspect in the murder of former Russian security agent Alexander Litvinenko for "services to the fatherland".

The Kremlin released an honors list including Andrei Lugovoi, a lawmaker in a nationalist party who is wanted by Britain over the poisoning of Litvinenko in 2006.

The United States on Monday delivered more than 100 pieces of military equipment to vulnerable NATO-allied Baltic states in a move designed to provide them with the ability to deter potential Russian threats.

The deliveries are intended to "demonstrate resolve to President (Vladimir) Putin and Russia that collectively we can come together," U.S. Major General John R. O'Connor told Agence France Presse as he oversaw the delivery of the equipment in the port of Riga.