Following a wave of bomb threats to Jewish community centres and desecrations at cemeteries throughout the United States the Department of Homeland Security is stepping up protection for American Jews.

"Over the past several weeks, the country has seen unacceptable and escalating threats and actual harassment directed at faith-based communities around the country, with a particular focus on threats to Jewish Community Centers," said Secretary of Homeland Security John Kelly in a statement on Wednesday 1 March.

Kelly said that on Wednesday he met with the executive directors of the Jewish Community Center Association of North America (JCC) to offer them advice. The group leads 150 community groups throughout the United States.

According to the Anti-Defamation League (ADL), more than 90 bomb threats have been called in to Jewish community gathering places since January.

The CEO of one Northeastern JCC told CNN, wishing to remain anonymous to guard against copycats, said: "This is the first time in the 60-plus years of our organisation we have had a bomb threat called in. And now we've had three bomb threats this year."

In early February more than 100 Jewish gravestones were vandalised in St Louis, and dozens of headstones at a Jewish cemetery in Philadelphia, Pennsylvania, were overturned last week.

On Wednesday the ADL reported that at least 20 bomb threats were made against JCCs and Jewish day schools on Monday this week. The group says it's the fifth wave of bomb threats since 1 January. New York was among the states where bomb threats were issued on Monday, including New York City.

"This is repugnant to everything we believe as New Yorkers," said New York Governor Andrew Cuomo as he toured an Albany JCC on Wednesday. "It is an act of cowardice."

Kelly said homeland security counter-terrorism experts will be offering Jewish communities in all 50 states "vulnerability assessments" for their buildings and meeting places, help getting training on bombing prevention and how to deal with a mass shooting attack, as well as other advice on how to improve security.

"Over the past 18 months, we've held active shooter preparedness workshops with Jewish Community Centers in San Francisco, Richmond, VA, Cherry Hill, NJ, and Miami, with more sessions planned in Columbus, Ohio, Wilmington, NC and Philadelphia," Kelly said.

The Trump administration has faced criticism for its slow response to denounce the anti-Semetic attacks. Last week the Anne Frank Centre for Mutual Respect released a scathing statement claiming that anti-Semitism has infiltrated the White House after US President Donald Trump failed to condemn the growing number of attacks for weeks. Earlier that day Trump spoke out against anti-Semitic "bigotry and intolerance" and said "it has to stop."

The centre's executive director Steven Goldstein said in a post on Facebook: "The president's sudden acknowledgment is a Band-Aid on the cancer of anti-Semitism that has infected his own administration."

Trump repeated his condemnation of anti-Semitism at the beginning of his joint address to Congress on Tuesday evening. "Recent threats targeting Jewish Community Centers and vandalism of Jewish cemeteries ... remind us that while we may be a nation divided on policies, we are a country that stands united in condemning hate and evil in all its forms," Trump said.

Kelly said in his statement: "The right to worship and commune within and across faiths is fundamental to the American experience and our way of life," adding that the DHS will be there to make sure they are better prepared and "to manage the consequences of incidents if they happen."

Mount Carmel Cemetery
A man looks at vandalised tombstones at Mount Carmel Cemetery in Philadelphia, Pennsylvania Mark Makela/Getty Images