Britain will double the number of long-range rocket launchers being sent to Ukraine, Ben Wallace announced on Wednesday as he said that Kyiv’s forces were right to hit Russian targets in occupied Crimea.
A “significant number of precision-guided missiles” with a range of 50 miles will also be supplied, Mr Wallace added.
It came as anonymous Ukrainian officials said that the country’s special forces and partisan resistance fighters were behind the unprecedented strike at the Novofedorivka airfield, 125 miles behind enemy lines, in Crimea.
At least 12 blasts rocked the Russian base, near the Black Sea resort of Saky, sending massive mushroom clouds billowing into the sky and holiday-goers fleeing.
Without confirming Ukrainian involvement, its air force boasted that nine Russian jets were completely destroyed in the strike.
Moscow rejected reports of missile strikes or sabotage at its base and blamed an accidental fire for the ammunition explosion, which analysts said was an attempt to cover up the ineffectiveness of Russian air defences.
For weeks, Ukrainian armed forces, with help from Western-provided long-range rocket launchers, have been battling to take back control of land towards the city, which was the first regional capital to fall into Russian hands.
Russian military bloggers suggested the attack on the Saky airfield had been carried out with US-provided long-range army tactical missile systems, which have a range of 190 miles.
“That air force base has been used by Russian forces to bomb Ukrainian targets. I think in anybody’s manual of war it would be a legitimate target,” the Defence Secretary said during a visit to Denmark.
“I’m not going to sit in judgment over Ukraine. Ukraine is sitting there fighting for its very survival.”
One official told The New York Times that the base, thought to be home to Russia’s 43rd Air Regiment, had been used as a key staging post for attacks in southern Ukraine.
Almost immediately after the explosions, pro-Kremlin channels on social media shared footage of a destroyed Su-24 fighter jet.
Satellite imagery taken prior to the blasts on Tuesday showed dozens of Russian aircraft lined up on the tarmac at the Saky airfield.
Oleksiy Arestovych, a military adviser to Volodymyr Zelensky, said that the attack was just the start of Ukrainian strikes on Russian targets in Crimea, which was illegally annexed by Russia in 2014.
He added that the next round of strikes were likely to happen “in the coming days”.
There were reports of traffic jams of over 60 miles as civilians attempted to escape the peninsula on Wednesday via the Kerch Strait Bridge to mainland Russia amid mounting fears of fresh attacks on the area.
Mr Arestovych said that if Ukraine’s armed forces could reach the border of Crimea, they would have the entire region covered with “all sorts of weapons” without having to enter it.
One official told the Politico news website that August and September would be “very important” months for Ukraine’s fightback.
Ahead of increasing Britain’s offering of multi-launch rocket launchers to six, Mr Wallace said that the war-torn country’s troops had been in the UK for extra training to be “much better” on the systems.
The additional military kit sent to Ukraine takes the UK’s total military support for Kyiv to £2.3 billion since the invasion began on Feb 24, more than any country other than the US.
Mr Wallace told reporters in Copenhagen: “It is very important that as Ukraine switches from Soviet-era equipment it uses the Western-gifted equipment in the way the West would use it, otherwise it would run out pretty quickly.
“It was very important when we gifted this [rocket system] that we said to the Ukrainians, ‘Look, you cannot use it in the same way. You have to be much better at discriminating about which targets you want to hit [and your] priorities’ and ensure we got a feedback loop to ensure it was worth carrying on giving those munitions.”
Western analysts said that the airbase attack on Tuesday had most likely been carried out by an unmanned aerial vehicle (UAV) evading Russia’s feeble air defence systems.
Justin Bronk, a research fellow at the Royal United Services Institute, said: “My best guess is that Ukrainian forces hit the base with a fairly small loitering munition or improvised UAV.”
A similar attack was carried out earlier this month at the Sevastopol naval base in Crimea, home to Russia’s Black Sea fleet.
The Institute for the Study of War, a US-based think-tank, said: “The Kremlin has little incentive to accuse Ukraine of conducting strikes that caused the damage since such strikes would demonstrate the ineffectiveness of Russian air defence systems.”