President Vladimir Putin intends to keep fighting in Ukraine until the West engages on his terms for peace, unfazed by Donald Trump's threats of tougher sanctions, and his territorial demands may widen as Russian forces advance, three sources close to the Kremlin said. Putin, who ordered Russian troops into Ukraine in February 2022 after eight years of fighting in country's east between Russian-backed separatists and Ukrainian troops, believes Russia's economy and its military are strong enough to weather any additional Western measures, the sources said.